The government is being urged not to encourage the expansion of private universities in England's higher education system.

Universities Minister David Willetts has suggested that he would bring forward legislation to enable this.

But UCU head Sally Hunt has warned against moving towards more US-style universities run for profit.

The private BPP University College said "a high-quality, self-funded higher education sector is vital".

Private universities have been suggested as a way of creating extra places in England's higher education system.

But the role of private universities in England has so far been limited - with tight regulation over the rights to award degrees.

And it is difficult for profit-making higher education firms to easily access public funds or their students to get fee loans through the state system.

Rapid growth

Last week, Mr Willetts told university leaders he would bring forward a Higher Education Bill that could include measures to allow private universities a greater role.

But the lecturers' union has written to Mr Willetts urging him not to make changes that would encourage more private companies to enter higher education in England.

In particular, they highlight concerns about the rapid growth of the for-profit sector in higher education in the United States - and questions raised in the US about the need for greater regulation.

Ms Hunt says in her letter to Mr Willetts that she is deeply concerned about any moves to mirror such growth in the for-profit sector in England.

She points to high-profile concerns in the US about the way for-profit universities have received public subsidies.

"I would ask that no further moves are made by this government, either now or in the wake of the Browne review's report, to make it easier for the for-profit sector to access public funds or the brand reputation of UK higher education," she says.

'Misleading'

BPP University College of Professional Studies gained university college status this year - the first private sector institution to get this status for more than 30 years.

The college says that it is "misleading" to make comparisons between the for-profit universities in England and the US, because the US has a "completely different approach to the regulation and funding of universities".

The private university also says it provides places without making any claim on public funds.

"BPP University College has never, nor does it have any future intentions to seek any funding from the the government," said a statement.

The government, under pressure on university places and funding, seems to be indicating that a university's status as public or private is not going to be the key issue.